Currently, metformin is one of the widely used medicaments in many fields, the major pharmacological effects of which are lowering blood glucose, curing poly-cystic ovary syndrome (PCOS), and reducing weight. As an oral anti-hyperglycemia agent, metformin can improve the tolerance of a patient with Type II diabetes mellitus on glucose, and reducing basal and postprandial concentration of plasma glucose; the morbidity of poly-cystic ovary syndrome in women of childbearing ages is as high as 6%, and it is one of the leading causes of anovulation infertilitas, metformin can ameliorate menstrual disorder, induce spontaneous ovulation, promote the ovary response of PCOS patient more amenable to physiological condition, avoid the development of excessive ovarian follicle, and reducing complications caused by those conditions.
A typical metformin compound is metformin hydrochloride. However, through recent clinical application, the disadvantage has been found that the homocystein concentration in the patient is substantially increased after long-term use of metformin hydrochloride, and the high homocystein concentration is a primary factor of a number of heart-brain diseases. Similarly, the sulfate, phosphate, hydrobromide, hydriodate, and the like of metformin cannot overcome the above problem. Nevertheless, other severe adverse effects of metformin compounds have not been described, and metformin compounds are recognized as a medicament with excellent therapeutic effect.
Accordingly, there is a great need for metformin compounds which can be used over a long period and do not result in increase of the homocystein concentration.